A known window regulator system determines a target window pane position by detecting the position of a user's fingertip, and drives a window regulator so as to move the window pane until the upper edge of the window pane coincides with the position of the user's fingertip. See JP2015-34459A. The position of the fingertip can be determined by using an optical detection device including a plurality of light emitters arranged along a side edge of a window frame and a plurality of light receivers arranged along the opposite side edge of the window frame.
According to this prior art, the light emitters and the light receivers are attached to the corresponding parts of the window frame. However, the window frame is formed by combining a number of different members such as an inner molding, window pane run channels, and so on, and some difficulty arises in positioning the light emitters and the light receivers in an adequately accurate manner. Also, some complications may arise in the assembly work.